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Title: Direct rate constant measurements for the reaction of ground-state atomic oxygen with ethylene, 244-1052 K

Abstract

The rate constant for the reaction of ground-state atomic oxygen with ethylene was determined by using two techniques: flash photolysis-resonance fluorescence (FP-RF, 244-1052 K) and discharge flow-resonance fluorescence (DF-RF, 298-1017 K). Kinetic complications due to the presence of molecular oxygen in the FP-RF experiments at high temperatures (T > 800 K) were overcome by using NO as the photolytic source of the O atoms. The rate constant, k/sub 1/ (T), derived in this study exhibits extreme non-Arrhenius behavior, but it can be successfully fit to the sum of exponentials expression, 244-1052 K, k/sub 1/(T) = (1.02 +/- 0.06) x 10/sup -11/ exp(-753 +/- 17 K/T) + (2.75 +/- 0.26) x 10/sup -10/ exp(-4220 +/- 550 K/T), in units of cm/sup 3/ molecule/sup -1/ s/sup -1/. Additionally, a fit of the results of this work to a simple transition-state theory expression and the comparison of these results with those of other workers are discussed.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY
OSTI Identifier:
6808827
DOE Contract Number:
AC02-76CH00016
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Phys. Chem.; (United States); Journal Volume: 91:6
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ETHYLENE; CHEMICAL REACTIONS; NITRIC OXIDE; PHOTOLYSIS; OXYGEN; GROUND STATES; CHEMICAL REACTION KINETICS; EXPERIMENTAL DATA; FLUORESCENCE; FLUORESCENCE SPECTROSCOPY; HIGH TEMPERATURE; LOW TEMPERATURE; MEDIUM TEMPERATURE; RESONANCE ABSORPTION; VERY HIGH TEMPERATURE; ABSORPTION; ALKENES; CHALCOGENIDES; DATA; DECOMPOSITION; ELEMENTS; EMISSION SPECTROSCOPY; ENERGY LEVELS; HYDROCARBONS; INFORMATION; KINETICS; LUMINESCENCE; NITROGEN COMPOUNDS; NITROGEN OXIDES; NONMETALS; NUMERICAL DATA; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; REACTION KINETICS; SPECTROSCOPY 400201* -- Chemical & Physicochemical Properties; 400500 -- Photochemistry

Citation Formats

Klemm, R.B., Nesbitt, F.L., Skolnik, E.G., Lee, J.H., and Smalley, J.F.. Direct rate constant measurements for the reaction of ground-state atomic oxygen with ethylene, 244-1052 K. United States: N. p., 1987. Web. doi:10.1021/j100290a057.
Klemm, R.B., Nesbitt, F.L., Skolnik, E.G., Lee, J.H., & Smalley, J.F.. Direct rate constant measurements for the reaction of ground-state atomic oxygen with ethylene, 244-1052 K. United States. doi:10.1021/j100290a057.
Klemm, R.B., Nesbitt, F.L., Skolnik, E.G., Lee, J.H., and Smalley, J.F.. 1987. "Direct rate constant measurements for the reaction of ground-state atomic oxygen with ethylene, 244-1052 K". United States. doi:10.1021/j100290a057.
@article{osti_6808827,
title = {Direct rate constant measurements for the reaction of ground-state atomic oxygen with ethylene, 244-1052 K},
author = {Klemm, R.B. and Nesbitt, F.L. and Skolnik, E.G. and Lee, J.H. and Smalley, J.F.},
abstractNote = {The rate constant for the reaction of ground-state atomic oxygen with ethylene was determined by using two techniques: flash photolysis-resonance fluorescence (FP-RF, 244-1052 K) and discharge flow-resonance fluorescence (DF-RF, 298-1017 K). Kinetic complications due to the presence of molecular oxygen in the FP-RF experiments at high temperatures (T > 800 K) were overcome by using NO as the photolytic source of the O atoms. The rate constant, k/sub 1/ (T), derived in this study exhibits extreme non-Arrhenius behavior, but it can be successfully fit to the sum of exponentials expression, 244-1052 K, k/sub 1/(T) = (1.02 +/- 0.06) x 10/sup -11/ exp(-753 +/- 17 K/T) + (2.75 +/- 0.26) x 10/sup -10/ exp(-4220 +/- 550 K/T), in units of cm/sup 3/ molecule/sup -1/ s/sup -1/. Additionally, a fit of the results of this work to a simple transition-state theory expression and the comparison of these results with those of other workers are discussed.},
doi = {10.1021/j100290a057},
journal = {J. Phys. Chem.; (United States)},
number = ,
volume = 91:6,
place = {United States},
year = 1987,
month = 3
}
  • The reaction of O(/sup 3/P) with methanol has been studied using the complementary discharge flow and flash photolysis techniques. In both cases, resonance fluorescence detection of atomic oxygen was employed. The discharge flow (DF) apparatus was used in a temperature range of 298--998 K while the flash photolysis (FP) apparatus was used in the overlapping range of 329--527 K. The apparent bimolecular rate constants for the O-atom/methanol reaction obtained from DF experiments at low temperatures (T< or =450 K) were independent of both the initial O-atom concentration and the mode of O-atom production. In addition, large excesses of O/sub 2/more » were added to the flow to intercept the primary reaction product (CH/sub 2/OH), but had no apparent effect on the measured rate constant. Results from the two methods were in good agreement within this limited temperature range (approx.300--500 K). At temperatures above approx.450 K, the apparent rate constants obtained from DF experiments were increasingly sensitive to the O/sub 2/ concentration, with the rate constants being smaller when determined in the presence of large (O/sub 2/). Since the initial O-atom concentrations were on the order of 10/sup 11/ or less, a simple stoichiometry effect can be ruled out. However, the results of the present kinetic experiments indicated that heterogeneous pyrolysis of CH/sub 3/OH may have occurred in the flow system. This observation is consistent with studies of the adsorption of methanol on silica surfaces. This problem was apparently overcome by adding small amounts of O/sub 2/ and the rate constants obtained in this way were seen to agree well with values extrapolated from the lower temperature DF and FP experiments. The rate data from DF and FP experiments were thus combined to obtain the following Arrhenius expression (298--998 K): k/sub 1/ (T) = (2.70 +- 0.50) x 10/sup -11/ exp(-5030 +- 160/RT cm/sup 3/ molecule/sup -1/ s/sup -1/.« less
  • The kinetics of the reaction of ethylene oxide with O(/sup 3/P) atoms has been investigated in detail using a discharge flow system with mass spectrometric and photometric detection. Absolute measurements of the rate constant, kinetic isotope effect, and stoichiometry have been made. The overall stoichiometry is 3 +- 1 oxygen atoms consumed per ethylene oxide molecule. Arrhenius parameters for the reaction of C/sub 2/H/sub 4/O with O are A = 10/sup (9.28+-0.08)/ L mol/sup -1/ s/sup -1/ and E = 5250 +- 150 cal mol/sup -1/ over the temperature range 298 to 691/sup 0/K, and Arrhenius parameters for the kineticmore » isotope effect are A/sub H//A/sub D/ = 0.9 +- 0.20 and E/sub D/--E/sub H/ = 1460 +- 230 cal mol/sup -1/, over the temperature range 482 to 691/sup 0/K. The magnitude of the preexponential factor and the temperature dependence of the isotope effect establish that hydrogen abstraction, rather than insertion to form a dioxetane intermediate, is the sole reactive channel for ethylene oxide plus O(/sup 3/P). The Arrhenius parameters are discussed and compared to other hydrogen abstraction reactions of O(/sup 3/P). Comparison is also made to the reactions of O(/sup 3/P) with other strained three-membered ring compounds. The final products H/sub 2/, H/sub 2/O, HCHO, CO, and CO/sub 2/ were identified, and a mechanism is proposed to account for their formation from the radical products of the initial step.« less
  • Recent years have seen great progress in modeling solvation effects on chemical reactions, especially ionic reactions and polar rearrangements. Radical chain reactions, in which a radical abstracts an atom from a molecule which is thereby converted to a radical, are an important class of reactions that has been less well studied. Such bimolecular radical substitution (S{sub R}2) reactions typically have smaller solvent effects than ionic reactions, and thus they provide a sensitive test of theory. The authors calculate the rate constant for the reaction {sup {sm_bullet}}H + CH{sub 3}OH {yields} H{sub 2} + {sup {sm_bullet}}CH{sub 2}OH both in the gasmore » phase and in aqueous solution at 298 K. To accomplish this, they apply two different methods to estimate the electronic energies along the reaction path.« less
  • Rate constants for the title reaction were measured by two independent techniques: flash photolysis-resonance fluorescence 300-1,001 K, and flash photolysis-shock tube, 915-1,341 K. In all cases, low-pressure-limit conditions prevailed. The data are well lifted, over the entire experimental temperature span (300-1,341 K), by the expression k{sub 1}{sup 0}(M = Ar) = (6.7 {plus minus} 0.1) {times} 10{sup {minus}32}(T/300){sup {minus}1.41 {plus minus} 0.02} cm{sup 6} molecule{sup {minus}2} s{sup {minus}1}. The present values, which fill in a gap in experimental measurements from 500 to 1,450 K, are compared to those of previous studies and evaluations. Also, the strong collision, low-pressure rate constantmore » (k{sub 1}{sup 0,SC}) and the collisional efficiency factor ({beta}{sub c}) are calculated over the temperature range 300-2,000 K, and {beta}{sub c} is compared with previously reported results.« less
  • The branching ratio, ..cap alpha../sub 1/, for the H + C/sub 2/H/sub 3/O product channel of the O(/sup 3/P) + C/sub 2/H/sub 3/O reaction was determined from measured H- and O-atom profiles in this flash photolysis-resonance fluorescence study. The relative detection sensitivity of the system for H and O atoms was determined experimentally. A chemical model was used to describe the reaction mechanism together with the relative detection sensitivity, and a value of ..cap alpha../sub 1/ = 0.27 +/- 0.05 was derived at 300 K. At higher temperatures, the value of ..cap alpha../sub 1/ appears to increase slightly. Possible reasonsmore » for this increase are discussed. 30 references, 2 figures, 7 tables.« less